I've taken two of the Postural Restoration Institute (PRI) seminars last year. I really like some of the concepts that are covered and valued how they made me look at things at a different angle. Each course has close to 100 different exercise and variance of a concept. One of the exercises I continually use is blowing up a balloon. It's a nice external cue for using your diaphragm and abdominal wall and creating a full exhale.
I'm continually surprised at how some people have the inability to actually blow up a balloon. They haven't breathed properly in years. They mouth breath. Taking air in through the mouth is junk air. It's the equivalent of eating junk food. You can survive, but you will get sicker/weaker over the years.
One of the correlations I see with the inability to breath well is a propensity to headaches, whether of the migraine or tension related type. Now, I'm at all saying learning to breath will get rid of migraine headaches. Please don't read into that. But, it's a been an interesting observation. There has been a reduction of the severity and frequency because of better breathing though.
A few reasons for the potential improvement.
1. Reduced tension throughout the scalene musculature. There exists an anterior, middle and posterior scalene. These are accessory breathing muscles and stabilizers. When we shallow breath, read breath up, (take a breath in and shoulders raise towards your ears) these muscles get chronically tight. Imagine doing a bad repetition of an exercise 20,000 times. This tension can create a lot of compression on the brachial plexus underneath the scalene. It can create stiffness in the front/side of the neck that makes movement much more difficult.
2. Reduced oxygen consumption at a chronic capacity. Never really read about the rate of decreased O2, but I rationalize that chronic decrease has to have a detrimental effect on tissue quality and well being.
3. Rib rotation occurs with breathing. Inhale has internal rotation, exhale has external rotation. We breath in better then we breath out. In the west we don't measure or teach a long exhale. Because of this we have locked internally rotated ribs. This can lead to ribs that jut towards the ceiling when laying on your back instead of pointing towards your pelvis. Weaker anterior core strength which potentially can create more psoas tension. Psoas tension has tremendous attachments into the diaphragm. Now we start a negative feedback loop of tension and breathing.
Breathing ladder type exercises after you have established a diaphragmatic pattern are an excellent tool to cement this in. My personal favorite are kettle bell swings. Swing it, set it down and take one breath in and out. 2 swings, 2 breaths. Work up to 10 and back down to 1. You will be tempted to really grab some quick cheap air, resist this urge. Only through the nose and out through the mouth. Can make this how you recover between your different sets of exercises as well.
Commit to breathing well and see how your health improves.